PROCESS FOR RECOVERING METALS FROM RECYCLED RECHARGEABLE BATTERIES

Abstract

The invention relates to hydrometallurgical method for recovering metals from spent energy storage devices. The method comprises combining aqueous hydrobromic acid leach solution and an electrode material of spent energy storage devices in a reaction vessel, dissolving the metals contained in the electrode material to form soluble metal bromide salts, removing elemental bromine, if formed, from the reaction vessel, separating insoluble material, if present, from the leach solution to obtain a metal-bearing solution and isolating one or more metals from said metal-bearing solution.

Claims

1) Hydrometallurgical method for recovering metals from spent energy storage devices, comprising combining aqueous hydrobromic acid leach solution and an electrode material of spent energy storage devices in a reaction vessel, dissolving the metals contained in the electrode material to form soluble metal bromide salts, removing elemental bromine, if formed, from the reaction vessel, separating insoluble material, if present, from the leach solution to obtain a metal-bearing solution and isolating one or more metals from said metal-bearing solution.

2) A method according to claim 1, wherein the electrode material comprises mixed metal oxide with one or more transition metals.

3) A method according to claim 2, wherein the electrode material comprises a cathode material of spent lithium ion batteries selected from the group consisting of lithium cobalt oxide (LiCoCO.sub.2), lithium manganese oxide (LiMn.sub.2O.sub.4) lithium manganese nickel oxide (Li.sub.2Mn.sub.3NiO.sub.8) and lithium nickel manganese cobalt oxide (LiNiMnCoO.sub.2).

4) A method according to claim 1, wherein the metals are isolated from the metal-bearing solution by precipitation, oxidative precipitation or electrodeposition.

5) A method according to claim 4, wherein metal isolation by precipitation is achieved by addition of a precipitating reagent to the metal-bearing solution, metal isolation by oxidative precipitation is achieved by addition of an oxidizer to the metal-bearing solution, and metal isolation by electrodeposition is achieved by cathodic deposition.

6) A method according to claim 1, comprising absorbing the elemental bromine liberated in the leaching step in an alkaline solution to create bromate-containing solution, and using said bromate-containing solution as an oxidizer for oxidative precipitation to isolate one or more metals from the metal-bearing solution.

7) A method according to claim 6, wherein the electrode material comprises manganese which is isolated from the metal-bearing solution by oxidative precipitation in the form of manganese dioxide with the aid of the bromate.

8) A method according to claim 5, wherein the electrode material comprises cobalt which is isolated from the metal-bearing solution by electrodeposition in the form of elemental cobalt.

9) A method according to claim 5, wherein the electrode material comprises nickel which is isolated by precipitation from the metal-bearing solution by addition of a precipitatior reagent which is a chelating agent.

10) A method according to claim 5, wherein the electrode material comprises lithium which is isolated by precipitation from the metal-bearing solution by addition of a precipitation reagent which is a water-soluble carbonate salt.

11) A method according to claim 4, comprising two or more of the following steps: isolating nickel by precipitation; isolating cobalt by electrodeposition; isolating manganese by oxidative precipitation; and isolating lithium by precipitation; wherein lithium is the last metal to be isolated.

12) A method according to claim 3, comprising isolation of cobalt and lithium.

13) A method according to claim 3, comprising isolation of manganese and lithium.

14) A method according to claim 3, comprising isolation of nickel, manganese and lithium.

15) A method according to claim 3, comprising isolation of nickel, cobalt and lithium.

16) A method according to claim 3, comprising isolation of nickel, cobalt, manganese and lithium.

17) A method according to claim 11, wherein: nickel is isolated by precipitation using dimethylglyoxime; cobalt is isolated by cathodic deposition on carbon; manganese is isolated by oxidative precipitation using bromate, said bromate being generated by absorbing in alkali hydroxide the elemental bromine which evolves during the leaching; and lithium is isolated by precipitation using alkali carbonate, carbon dioxide or alkali hydroxide.

18) A method according to claim 16, wherein the metals are isolated from the metal-bearing solution by the following sequence of steps: adding chelating agent to the metal-bearing solution to precipitate a nickel complex, separating the nickel complex and collecting Ni-depleted metal bearing solution; electrodepositing cobalt from the Ni-depleted solution, to obtain cobalt deposit onto a cathode surface and collecting Ni, Co-depleted solution; adding an oxidizer to Ni, Co-depleted solution to precipitate an oxide of manganese, separating said oxide of manganese and collecting Ni, Co and Mn-depleted metal bearing solution; adding a water-soluble hydroxide, a water-soluble carbonate or carbon dioxide to said Ni, Co and Mn-depleted metal bearing solution to precipitate lithium hydroxide or carbonate and separating the lithium hydroxide or carbonate.

Description

EXAMPLES

[0039] Methods

[0040] Inductively coupled plasma (ICP) was used to determine metal content in the feedstock and in solution; the ICP instrument was ICP VISTA AX, Varian Ltd or ICP 5110, Agilent Technologies. Recovery percentage (yield) was calculated, e.g., by [M]solution/[M]feedstock×100, where [M] indicates the measured weight of metal M in the solution and the feedstock, respectively.

Example 1 (of the Invention) and 2 (Comparative) LiCoO.SUB.2 .Leaching with Hydrobromic Acid (of the Invention) and Hydrochloric Acid (Comparative)

[0041] LiCoO.sub.2 (1.5 g, purchased from Sigma Aldrich) was added to a vessel that was previously charged with 98.5 g of an aqueous solution of the hydrohalic acid (15 wt %). The dissolution tests were carried out at 56.4° C. under stirring over a time period of two hours. When HBr was used, a reddish solution was formed, indicative of the evolution of elemental bromine. Bromine vapors were absorbed in a column charged with sodium hydroxide. Results of the leaching test are set out in Table 1.

TABLE-US-00001 TABLE 1 Leaching Cobalt Lithium Example agent recovery (%) recovery (%) 1 Hydrobromic acid 96.22 85.68 2 Hydrochloric acid 71.68 76.76

Example 3 (of the Invention) and 4 (Comparative) LiMn.SUB.2.O.SUB.4 .Leaching with Hydrobromic Acid (of the Invention) and Hydrochloric Acid (Comparative)

[0042] LiMn.sub.2O.sub.4 (1.5 g, purchased from Sigma Aldrich) was added to a vessel which was previously charged with 98.5 g of an aqueous solution of hydrohalic acid (15 wt %). The dissolution tests were carried out at 40° C. under stirring over a time period of 10 minutes. For HBr, a reddish solution was formed, indicative of the evolution of elemental bromine. Bromine vapors were absorbed in a column charged with sodium hydroxide. Results of the leaching test are set out in Table 2.

TABLE-US-00002 TABLE 2 Leaching manganese lithium Example agent recovery (%) recovery (%) 3 Hydrobromic acid 86.30 88.50 4 Hydrochloric acid 55.90 83.24

Examples 5 to 7

Leaching of Lithium Metal Oxides with Hydrobromic Acid in the Presence of Graphite

[0043] To assess the ability of hydrobromic acid to dissolve lithium metal oxides effectively in the presence of added graphite (the anode material in lithium-ion batteries), the procedure described in previous examples was repeated with the addition of graphite to the vessel. The experimental conditions (leaching temperature and time, acid concentration and concentration of lithium metal oxide in the acid solution) and the results are set out in Table 3 below (average results based on triplicate repetition). Graphite/pure metal oxide weight ratio was ⅛ in all experiments.

TABLE-US-00003 TABLE 3 transition HBr T time metal lithium Ex. Li.sub.xM.sub.yO.sub.z (wt %) (wt %) (° C.) (h) recovery (%) recovery (%) 5 LiCoO.sub.2 15 60 2 Co: 92.7 82.10 6 LiMn.sub.2O.sub.4 15 25 2 Mn: 98.8 84.8 7 Li.sub.2Mn.sub.3NiO.sub.8 15 90 2 Mn: 100 74.09 Ni: 97.8

[0044] The results indicate that the presence of graphite (the anode material in lithium ion batteries that may be part of the black mass isolated by the recycling industry) does not interfere with the good leaching action of hydrobromic acid.

Example 8

Effect of Temperature and Acid Concentration on the Leachability of Lithium Metal Oxides with Hydrobromic Acid

[0045] The leachability of lithium mixed metal oxide (for example LiNiCoAlO.sub.2) was investigated over a broad concentration range of acidic leach solution at 50° C. The general procedure consists of adding the mixed metal oxide to hydrobromic acid solutions with varying concentration (15 wt %, 24 wt % and 35 wt %), keeping the leach solution under heating at the selected temperature and recording the period of time until full dissolution of the added solid is observed (determined by visually inspecting the sample). Solid/liquid ratio was constant at (1/99) in all tested samples.

[0046] The leaching times are tabulated in Table 4. It is seen that at around 50° C., dissolution of the lithium mixed metal oxide is achieved fairly rapidly for all three test solutions. That is, across the 15-35 wt % concentration range.

TABLE-US-00004 TABLE 4 HBr concentration, Temperature, Time, wt% ° C. min 15 50 22 24 50 10 35 50 3

Example 9

Isolation of Metals by Electrodeposition

[0047] A series of electrodeposition tests was performed. The experimental set-up consists of a two-compartment flow cell. The two compartments were separated by a separator film. Carbon felts with a surface area of 1000-1500 m.sup.2/gr were used as electrodes supported by carbon plates as current collectors (the weight of the felts was about 0.4 gr). A reference Ag/AgCl electrode was used to monitor the electrodes redox potential.

[0048] 118 grams of a cobalt-containing leachate (obtained as shown by previous examples) were added to the 0.2 L cathodic compartment. The counter solution added to the anodic side was 35% wt NaBr solution. The flow cell was connected to the catholyte and anolyte reservoirs and the solutions were recirculated parallelly through the counter flow cell.

[0049] Elemental cobalt was electrodeposited on the felt at the cathode half-cell by using a chronopotentiometry method, in which a constant current is supplied to the electrode and a sudden change in the measured potential indicates that the electrodeposition reaction was completed. In each experiment, a constant current in the range between 1 and 3 A was applied. For a solution with 4.7 wt % Co.sup.2+, the electrodeposition process with a current of 3 A ended approximately after 90 minutes.

Example 10

Recovering Manganese from Black Mass by Leaching Followed by Oxidative Precipitation with Bromate

[0050] Leaching Step

[0051] 300 gram of cathode material (black mass obtained from a recycling company) were added to 1700 grams of 35% wt hydrobromic acid solution that was heated to 60° C. prior to the addition of the black mass.

[0052] The mixture was stirred over 3 hours and then filtered to separate the residual solids from the aqueous solution. The filtrate, consisting of the metals-bearing solution, was collected. The filter cake was washed with 50 grams of slightly acidic DW (pH=4-6) solution and the washing solution was combined with the filtrate.

[0053] Bromine that evolved during the leaching stage was absorbed in a 15-25% (% wt) sodium hydroxide scrubber until NaOH concentration was decreased to 5%.

[0054] Separation of Manganese from the Filtrate

[0055] 1500 gram of the filtrate were charged to a 2 L reactor. The scrubber solution, consisting of BrO.sub.3.sup.−, Br.sup.− and NaOH was added to the reactor until the pH value was steady in a range of 3.5<pH<5. The precipitate, consisting of manganese oxide was separated by filtration and the manganese-free filtrate was collected.

Example 11

Sequential Recovery of Nickel, Cobalt and Manganese from Black Mass by Leaching Followed by Selective Precipitation, Electrodeposition and Oxidative Precipitation

[0056] Leaching Step

[0057] 240 gram of cathode material (black mass obtained from a recycling company) were gradually added over thirty minutes to 960 grams of 48% wt hydrobromic acid solution that was heated to 60° C. prior to the addition of the black mass. After the addition was completed, the reaction mixture was stirred for three hours. The sample was filtered on a Buchner with 56 mm glass-fiber filter under vacuum. Metal concentrations were analyzed using ICP.

[0058] Bromine that evolved during the leaching stage was absorbed in a 15-25% (% wt) sodium hydroxide scrubber until NaOH concentration was decreased to 5%.

[0059] The leaching yield of various metals is tabulated in Table 5.

TABLE-US-00005 TABLE 5 Li Ni Co Mn yield, % yield, % yield, % yield, % 96.2 93 94 94.7

[0060] Selective Separation of Metals from the Leachate

[0061] Nickel, cobalt and manganese were consecutively separated from the leachate:

[0062] Ni was recovered from the leachate by selective precipitation with the aid of dimethylglyoxime. 4.2 gr dimethylglyoxime (DMG) were added to 987.4 gr leachate that contained 0.11 wt % Ni, such that the molar ratio DMG:Ni was 2:1. The pH of the mixture was raised to pH=4.4 using 91.5 gr of 20 wt % Na.sub.2CO.sub.3 solution. When the pH value reached pH=3.5, the leachate attained a pinkish color. The leachate was filtered on 110 mm Whatman grade 41 ash less filter paper.

[0063] The composition of the mother liquor, obtained after the precipitation and filtration of nickel bis(dimethylglyoximate), was analyzed to determine nickel (and other metals) percentage removal. Results are tabulated in Table 6, indicating the selectivity of the precipitating reagent towards nickel removal.

TABLE-US-00006 TABLE 6 Ni Li Co Mn removal, % removal, % removal, % removal, % 87 6.9 0 0

[0064] Next, cobalt was recovered from the nickel-depleted leachate by electrodeposition. 67.5 gr of the nickel-depleted leachate solution with 4.7 wt % CO.sup.2+ was added to the cathodic side of the divided electrochemical flow-cell that was described in Example 9. The solution in the anodic side consisted of 35 wt % aqueous sodium bromide. Circulation rates generated by the peristaltic pump (Watson Marlow 323) in the flow cell were 40-60 rpm. A current of 3 A was applied over a period of 90 minutes. pH was maintained at 4-4.5 by addition of sodium hydroxide solution.

[0065] At the end of the electrolysis, it was found that the weight of the catholyte decreased to 53.7 gr. The weight of the carbon felt which served as cathode increased by ˜2.9 gr. The felt and the membrane separator were placed in 24 wt % HBr at 45° C. for 3 hours, to dissolve the metal plating formed during the electrolysis. The resultant solution was filtered on 70 mm glass fiber filter (Whatman). Filtrate was analyzed to determine the composition of the electroplated metals. Results are tabulated in Table 7, indicating the selectivity of the electrolysis towards cobalt removal.

TABLE-US-00007 TABLE 7 Other Metal Co Li Ni Mn metals Wt % in the 91.46 0.96 0.54 5.6 ~1.0 electroplating

[0066] Next, manganese recovery was achieved with 25 wt % NaBrO.sub.3 solution. 900 gr NaBrO.sub.3 solution were gradually added to 738 gr of the nickel-cobalt depleted leachate solution over one hour. During the NaBrO.sub.3 addition, the pH value increased from pH<1 to pH≈4. A precipitate was formed. The sample was filtered on a 110 mm Whatman grade 41 ash less filter paper. The wet cake weight was 24.8 gr, and filtrate weight was 1576 gr. Removal percentage of metals from the solution are tabulated in Table 8, indicating the selectivity of this stage towards manganese removal.

TABLE-US-00008 TABLE 8 Mn Li Ni Co removal, % removal, % removal, % removal, % 93.3 5 8.2 5.5